Offensive missiles such as any number of cruise missiles, are constructed to fly at low altitudes (i.e., just above tree tops or water surfaces) so as to avoid detection by the targeted party's radar. In such a situation a targeted ship, for example, may have just a few seconds to first identify the thread and then take countermeasures, such as the launching of one of its defensive missiles.
Typically, a land or ship born defensive missile is launched from a canister or missile launcher in a generally vertical direction. Such a defensive missile must attain a sufficient velocity before its airfoil surfaces are able to perform any substantial maneuvers. This generally translates into having the missile reach an altitude of thousands of feet before it is able to pitch over and begin seeking the incoming missile threat. For long range threats this high altitude pitch over is a common design characteristic and is therefore a common element in existing defense missile systems.
Given the low altitudes of threat missiles and the consequential small window for identification and reaction, such a high altitude for pitch over is problematic. More specifically, given the limited timeframe to successfully determine an intercept solution and the high speeds of the threat missiles, it may not be possible to optimize the intercept trajectory due to the lack of launch maneuverability and stability. There exists a very real possibility of overshooting the target or expending too much time and fuel with large arching course corrections resulting in missed intercept opportunities.
Common missile control systems incorporate a number of different technologies by which guidance control and vehicle stability are provided to a missile, however attempts to adapt these systems to address this low speed guidance control and stability problem have not been complete.
Control surfaces such as wings and canards that are actuated during flight essentially interrupt the airflow around the missile body for high speed control authority. If sized for high speed use they are ineffective at low speeds. If sized for low speed they are large, heavy and likely not to fit within the launch frame or canister.
Movable nozzle systems are heavy and complicated. As they are not detachable they add to the overall vehicle weight and degrade overall performance after they have fulfilled their purpose at low speed. In addition, nozzle systems frequently do not provide sufficient thrust vector angles as are required for low speed guidance control and vehicle stability to meet a rapidly approaching low altitude threat that has been detected only a short time period away from impact.
Thrust vector control (“TVC”) systems typically incorporate movable nozzles, jet tabs, or jet vanes, the latter offering roll control but substantially degrading rocket motor kinematic performance by impinging propellant flow. TVC thrust redirection systems steer the missile from the aft rocket nozzles. These systems are ineffective after motor burn-out and again are often heavy and costly devices resulting in significant vehicle weight increase and subsequent overall missile performance degradation.
Missile jet vane control systems have been shown to be effective at providing low speed guidance control and stability. However, as the jet vanes are placed in the flow of the missile exhaust they do impact missile motor performance. In addition, jet vane control systems require the use of low smoke, low energy propellant grains to enable the jet vanes to survive the nozzle plasma flow environments and are therefore not suitable for use with many currently existing and intended rocket motor designs.
Moreover, despite various prior art attempts, missile control at launch and within the period after launch before the missile obtains sufficient high speed velocity to utilize its traditional control surfaces has remained problematic and elusive. Given the large variety of currently existing defensive missile inventories, individualized customization and/or modification is undesirable. The redesign of motors is both costly and time intensive and may in many cases lead to additional disposal costs of hazardous materials as fuel systems are replaced.
Hence, there is a need for a missile stabilization system that overcomes one or more of the issues and problems identified above.